The   Dor variable HD 164615: results from a multisite photometric campaign

Zerbi, F. M.; Rodríguez‐López, C.; Garrido, R.; Martín, S.; Akan, K.; Luedeke, K. D.; Keskin, V.; İbanoǧlu, C.; Evren, S.; Tunca, Z.; Pekünlü, R.; Paparó, M.; Nuspl, J.; Krisciunas, K.; Jiang, S. Y.

doi:10.1093/mnras/292.1.43

Cited by 35 publications

(21 citation statements)

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“…Investigating two frequencies (1.32 d −1 and 1.40 d −1 ) deduced from multisite photometry of HD 108100, Breger et al (1997) concluded that amplitude ratios and phase differences between the light curves at different wavelengths are consistent with g-mode pulsation of = 1, rather than = 2. For two of four frequencies observed in HD 164615, Zerbi et al (1997) Hatzes (1998) found that the m = 2 mode seems to be consistent with the amplitude of the radial velocity variations. A preliminary mode identification based on the observed color curves of HD 218396 from a multisite campaign (Zerbi et al 1999) Kaye et al (1999b) have shown that the observed periodic (2.6 days) variations are the result of high-order (n), low-degree ( ), non-radial g-mode pulsation.…”

Section: Comparison With Previous Mode Identifications In γ Doradus Smentioning

confidence: 75%

Non-radial pulsations in the γ Doradus star HD 195068

Jankov

Mathias

Chapellier

et al. 2006

A&A

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We present high resolution spectroscopic observations of the γ Doradus star HD 195068. About 230 spectra were collected over 2 years. Time series analysis performed on radial velocity data shows a main peak at 1. −1 can be successfully modeled by a non-radial pulsation mode = 5 ± 1, |m| = 4 ± 1. For the intermediate frequency 1.27 d −1 we deduce = 4 ± 1, |m| = 3 ± 1. Evidence that the star is not pulsating in the radial mode ( = 0) rules out a previous classification as an RR Lyrae type star. We investigate the time variability of FDI power spectra concluding that the observed temporal variability of modes can be explained by a beating phenomenon between closely spaced frequencies of two non-radial modes. The distribution of the oscillation power within the line profile indicates that there is a significant tangential velocity component of oscillations characteristic of high radial order gravity modes which are predicted to be observed in γ Doradus type stars.

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Section: Comparison With Previous Mode Identifications In γ Doradus Smentioning

confidence: 75%

Non-radial pulsations in the γ Doradus star HD 195068

Jankov

Mathias

Chapellier

et al. 2006

A&A

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“…According to its spectral type, 57 Tau is situated on HR diagram near to the cool border of the instability strip, exactly in the region where γ Dor stars are located. The g−mode frequencies of γ Dor stars discovered in the last few years (Abt et al 1983;Antonello & Mantegazza 1986;Krisciunas & Guinan 1990;Balona et al 1994;Breger et al 1997;Zerbi et al 1997;Kaye et al 1998;Kaye et al 1999a) occur in the same frequency range as in the low frequency domain of 57 Tau's amplitude spectrum. If this interpretation is correct 57 Tau would be the first δ Scuti type star where both p & high overtone g modes are excited, i.e.…”

Section: Discussionmentioning

confidence: 92%

A comprehensive study of the δ Scuti star, 57 Tauri (= HR 1351) in the Hyades cluster

Paparó

Rodríguez²,

McNamara

et al. 2000

Astron. Astrophys. Suppl. Ser.

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Abstract.A comprehensive frequency analysis of 57 Tau, supposed only a static pulsational arrangement, is presented based on 54 nights of photometric data collected between 1981 and 1995 (althogether 232 hours). The presence of individual frequencies is confirmed by intercomparing four subsets of this data set, however, the uncertainties in data coming from the sparse nights and low signal weaken the conclusion on some results. The entire data base is then used to resolve closely spaced peaks. Twelve frequencies are indentified using this process. Further multisite observations are recommended to confirm the present frequency solution. Two periods, with a high probability of being real, are found in the low frequency domain. They are suggested to arise from binarity or g modes, as in γ Dor stars. Single unusual cycles, possessing large amplitude, or displaying asymmetry, have been localized. A coherent frequency at 29.83 c/d with variable amplitude was found. The nonstandard behaviour of the light variation indicates that nonlinear and/or nonstationary processes could be very important in the investigation of δ Scuti observations.

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“…10. A comparison of log g values derived from Geneva photometry and from other sources (photometry and spectroscopy) 6 Rodríguez & Breger (2001); Rodríguez et al (2000); ; Poretti et al (1997);Breger et al (1997); Zerbi et al (1997Zerbi et al ( , 1999; Aerts et al (1998); Kaye et al (1999b); Gray & Kaye (1999) indicates a systematic difference of about 0.4 dex for log g values above 4.35 dex as calculated from the Geneva photometry (Cuypers & Hendrix, priv. comm.).…”

Section: Characterization Of Stars That Show No Clear Periodic Variabmentioning

confidence: 99%

TheKeplercharacterization of the variability among A- and F-type stars

Uytterhoeven

Moya

Grigahcène

et al. 2011

A&A

325

316

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Context. The Kepler spacecraft is providing time series of photometric data with micromagnitude precision for hundreds of A-F type stars. Aims. We present a first general characterization of the pulsational behaviour of A-F type stars as observed in the Kepler light curves of a sample of 750 candidate A-F type stars, and observationally investigate the relation between γ Doradus (γ Dor), δ Scuti (δ Sct), and hybrid stars. Methods. We compile a database of physical parameters for the sample stars from the literature and new ground-based observations. We analyse the Kepler light curve of each star and extract the pulsational frequencies using different frequency analysis methods. We construct two new observables, "energy" and "efficiency", related to the driving energy of the pulsation mode and the convective efficiency of the outer convective zone, respectively. Results. We propose three main groups to describe the observed variety in pulsating A-F type stars: γ Dor, δ Sct, and hybrid stars. We assign 63% of our sample to one of the three groups, and identify the remaining part as rotationally modulated/active stars, binaries, stars of different spectral type, or stars that show no clear periodic variability. 23% of the stars (171 stars) are hybrid stars, which is a much higher fraction than what has been observed before. We characterize for the first time a large number of A-F type stars (475 stars) in terms of number of detected frequencies, frequency range, and typical pulsation amplitudes. The majority of hybrid stars show frequencies with all kinds of periodicities within the γ Dor and δ Sct range, also between 5 and 10 d −1 , which is a challenge for the current models. We find indications for the existence of δ Sct and γ Dor stars beyond the edges of the current observational instability strips. The hybrid stars occupy the entire region within the δ Sct and γ Dor instability strips and beyond. Non-variable stars seem to exist within the instability strips. The location of γ Dor and δ Sct classes in the (T eff , log g)-diagram has been extended. We investigate two newly constructed variables, "efficiency" and "energy", as a means to explore the relation between γ Dor and δ Sct stars. Conclusions. Our results suggest a revision of the current observational instability strips of δ Sct and γ Dor stars and imply an investigation of pulsation mechanisms to supplement the κ mechanism and convective blocking effect to drive hybrid pulsations. Accurate physical parameters for all stars are needed to confirm these findings.

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The Dor variable HD 164615: results from a multisite photometric campaign

Cited by 35 publications

References 0 publications

Non-radial pulsations in the γ Doradus star HD 195068

Non-radial pulsations in the γ Doradus star HD 195068

A comprehensive study of the δ Scuti star, 57 Tauri (= HR 1351) in the Hyades cluster

TheKeplercharacterization of the variability among A- and F-type stars

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